Inspection and monitoring of various properties and conditions of a substance is essential in various technical fields, including production processes of said substance. For example, dielectric spectroscopy may be used for inspecting and monitoring biological cells, such as monitoring and imaging cell growth in fermentation as described by Asami et al., in “Dielectric spectroscopy of biological cells”, 1996, Bioelectrochem. Bioenerg. 40:141-145
A system for real time measurement and control of humidity in dielectric fluid substances is described in Patent Publication No. ES 2160468, wherein absorbed microwave energy passed through a dielectric material is used to estimate water content of the material in real time during an industrial process.